Study of the composition, processing and microstructure relationship of light alloys

Sumayli, Abdulrahman Idris

Abstract

This research consists of two main parts. The first part concerns the study of the effect of pulse electromagnetic fields on the microstructural evolution and the hardness of an Al-20%Si alloy. A pulse magnetic field apparatus is used to produce different magnetic field fluxes during the solidification of an Al-20%Si alloy. The size of the primary Si particles of the alloy is reduced to ~6 times (from 14078.7 μm2 to 2427.3 μm2) when the peak pulse magnetic field flux was increased from 0 to 1.4 T. In addition, the magnetic field resulted in the formation of lamellar Al + Si eutectic colonies, and more uniformed eutectic Si in the matrix. Such structure refinement increased the hardness of the alloy from 65 to 75 (Vickers hardness).
The second part of the research is to study the composition-microstructure relationship and corrosion properties of three Mg-Gd based alloys. The alloys used are (1) Mg-10%Gd, (2) Mg-10%Gd-0.4%Zr and (3) Mg-5%Gd-5%Nd-0.4%Zr (weight percentage). The focus of the research is to investigate the effects of adding Nd and Zr on the changes of phases and structures. Very effective grain refinement effect for the alloys were found when adding Nd and Zr, decreasing the size of Gd cuboids, and resulting in higher hardiness for the Mg-5%Gd-5%Nd-0.4%Zr. The mechanism is mainly due to the precipitation hardening and grain boundary strengthening. In addition, the corrosion behaviour is also tested in the Hank’s solution. Noticeably, corrosion rate of the master alloy increased when alloyed with Nd and Zr.

Citation

Sumayli, A. I. Study of the composition, processing and microstructure relationship of light alloys. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4508161

• Thesis Type: Thesis
• Deposit Date: Jan 9, 2024
• Publicly Available Date: Jan 9, 2024
• Keywords: Mechanical engineering
• Public URL: https://hull-repository.worktribe.com/output/4508161
• Additional Information: School of Engineering and Computer Science; University of Hull
• Award Date: Mar 1, 2022